Cooling plate and manufacturing method thereof, and sputtering target and manufacturing method thereof

ABSTRACT

The present invention is a cooling plate including a groove, which becomes a passage of a coolant, inside a body, wherein one or more fins are provided inside the groove, wherein the groove is covered with a lid having width larger than the groove, wherein the lid is joined to the body by friction stir welding, and wherein a weld bead formed by: the joining is outside the passage, and the weld bead formed by the joining is formed within the body and further, is characterized by a manufacturing method of a cooling plate that has a first groove, which becomes a passage of a coolant, and a second groove, which has width larger than the first groove and receives a lid on the first groove, inside a body, receives the lid on the second groove, and is joined to the body, the manufacturing method of a cooling plate wherein, while the lid and the body are joined together by the friction stir welding owing to insertion of a-rotation tool having a shoulder and a pin, the joining is performed so that a weld bead formed by the joining may become out of the passage, and furthermore, is characterized in that a target for sputtering is joined to the cooling plate.

This application is a continuation of prior U.S. patent application Ser.No. 10/828,834, filed Apr. 21, 2004, the entire disclosure of which isincorporated herein, which is a continuation of prior U.S. patentapplication Ser. No. 10/024,598, abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a new cooling plate and a manufacturingmethod thereof, a sputtering target and a manufacturing method thereof,a backing plate and a manufacturing method thereof, and a sputteringtarget and a manufacturing method thereof.

PRIOR ART

Although a cooling plate is widely used industrially, an efficientcooling function is required. For example, in a sputtering apparatus,efficient radiation of the heat generated in a target material affectsthe performance of a thin film that is obtained. In particular, in thecase of a sputtering apparatus for a liquid crystal manufacturingapparatus, a target material with a large area is used, which radiatesplenty of heat. For this reason, a backing plate is used as a coolingplate, the backing plate having a channel inside a smooth plate composedof copper, a copper alloy, aluminum, or an aluminum alloy, and havingthe structure that the channel is covered with a lid and the lid andcooling plate are metallically joined to be sealed. Up to now, thejoining of a body of a backing plate and a lid is performed bymetallically joining them by electron beam welding, diffusion bonding, abrazing method, etc. In addition, besides the backing plate, variouskinds of water cooled jackets, water-cooled chills, etc. are used as aheat sink, and every one has the structure of having a channel thereinsimilarly to the above-described backing plate.

Moreover, it is necessary for a backing plate used for a liquid crystalmanufacturing apparatus to support a target material at a sputteringstep, and to have an efficient cooling function. For this reason, thebacking plate has a channel inside a smooth plate composed of copper, acopper alloy, aluminum, or an aluminum alloy, and has the structure thatthe channel is covered with a lid and the lid and cooling plate aremetallically joined to be sealed up to now, the joining of a body of abacking plate and a lid is performed by metallically joining them byelectron beam welding, diffusion bonding, a brazing method, etc.

In regard to the manufacture of this backing plate, there isJP-A-2000-73164 specification, where a backing plate is shown, where aplate-like cooling section that has a coolant passage inside isintegrated with a plate-like base section by friction stir welding.

Since a backing plate needs to enhance cooling effectiveness, goodflatness and smoothness are required of a surface of the backing platethat contacts with a target material etc. Up to now, the joining of abody of a backing plate and a lid covering a channel is performed byelectron beam welding, laser welding, diffusion bonding, a brazingmethod, etc. However, since it is necessary to make a surface flat bycorrection or machining after joining because these welding methods havelarge heat distortion after joining, they have problems in respect ofquality, and accuracy, and further productivity and cost.

Furthermore, in the above-described known example, although thestructure that a target is provided through a plate-like base sectionprovided on a plate-like cooling section which has a coolant passage isshown, not only direct cooling cannot be obtained, but also theformation of a compact cooling passage cannot be obtained.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a cooling plate, whichhas high cooling effectiveness and a thin, large area, and amanufacturing method thereof, and a sputtering target and amanufacturing method thereof.

The present invention is a cooling plate characterized in that a groove,which becomes a passage of a coolant, is provided inside a body, thatthis groove is covered with a lid with width larger than the groove,that the lid is joined to the body by friction stir welding, and that aweld bead formed by the welding is outside the passage.

Furthermore, the present invention is a cooling plate characterized inthat grooves, which become passages of several independent coolants, areprovided inside a body, that the groove is covered with a lid, that thelid is joined to the body by friction stir welding, and that a weld beadformed by the joining is outside the passage.

Moreover, the present invention is a cooling plate characterized inhaving any one or combination of the structure that a groove, whichbecomes a passage of a coolant, is provided inside a body, the groove iscovered with a lid, the lid is joined to the body by friction stirwelding, and at least an end of a weld bead formed by the joining isformed in the body except a joining, the structure that a groove, whichbecomes a passage of a coolant, is provided inside a body, the groove iscovered with a lid with width larger than the groove, the lid has one ormore fins, the groove is covered with a lid with width larger than thegroove, the lid is joined to the body by friction stir welding, and aweld bead formed by the joining is outside the passage, and thestructure that the passage is a passage closed within the body, an airvent is provided in a portion forming the passage, and at least an endportion of the weld bead of the joining is formed except the joining.

In particular, since the present invention performs joining with fittinga lid, which covers a groove., into the groove to a body where thegroove with a path as a closed channel is formed, there is no mutualexpansion of matching sections. Hence, not only good joining can beobtained, but also there is no excessive joining because the body itselfis in one piece, and hence it is possible to obtain a cooling plate witha compact thin shape is obtained also in a large area regardless of anarea.

The channel is at least one of an I-shaped channel, a U-shaped channel,an S-shaped channel, and an M-shaped channel, a round channel, and aspiral channel, and it is preferable that one or more of them are used.Since each channel has a closed path, an entrance and an exit arelocated in each path. Hence, each entrance and each exit are connectedin parallel in two or more channels, and hence, uniform cooling can beperformed as the whole cooling plate. It is preferable to join thechannels so that more uniform cooling may be performed.

Although it is preferable that the body and lid are composed of copper,a copper alloy, aluminum, an aluminum alloy, titanium, or stainlesssteel, the former having higher heat conduction is more preferable.

The present invention is a manufacturing method of a cooling plate thathas a first groove, which becomes a passage of a coolant, and a secondgroove, which has width larger than the first groove and receives a lidon the first groove, inside a body, places the lid on the second groove,and is joined to the body, the manufacturing method of a cooling platebeing characterized in that, while the lid and the body are joinedtogether by friction stir welding owing to the insertion of a rotationtool having a shoulder and a pin, the joining is performed so that aweld bead formed by the joining may become outside the passage. Theabove-described joining method can perform joining at a temperature of afusing point of copper or aluminum or lower. Furthermore, theabove-described joining performs joining in a coolant such as water,oil, or an inert gas, or with compulsorily cooling the lid and body bypouring the above-described coolant near the joining.

A friction stir welding method according to the present invention is amethod of performing joining with using frictional heat and plastic flowwhich are generated between the rotation tool and joining material byrotating and inserting a rotation tool which has a shoulder and a pinthat are made of material harder than the aluminum or a copper alloysubstantially and relatively moving the joined material. This isdisclosed by National Publication of the Translated Version of PCTApplication No. 7-505090 specification, etc. That is, since a plasticflow phenomenon by the frictional heat between the rotation tool andjoined material is used, this is different from conventional weldingsuch as electric arc welding and electron beam welding, but does notperform joining (welding) with melting the joined material. Furthermore,the friction stir welding method differs from a method of rotatingworkpiece like a conventional friction welding method performing joiningwith frictional heat, but is a method of being able to continuously joina workpiece in the longitudinal direction of a joining line below afusing point of the joining material.

By using the friction stir welding method, since it is possible toperform joining at a low temperature below the fusing point of a joiningmaterial, distortion by the joining is small in comparison with aconventional welding method, and hence a cooling plate with highaccuracy can be manufactured. Hence, it is possible to simplify thecorrection step after joining, and to reduce cost by shorteningcorrection work-hours.

Furthermore, this joining method can perform joining in a coolant suchas water, oil, or an inert gas, or with pouring the above-describedcoolant near the joining. At this time, since it is possible to suppresstemperature rise in a position apart by several mm from the joining, itis possible to suppress heat distortion after joining to the minimum.Hence, it is possible to make a face, which contacts to the siliconwafer, smooth and accurate, and therefore, to manufacture a reliablebacking plate.

Namely, the present invention is a manufacturing method of a backingplate that is made of copper, a copper alloy, aluminum, or an aluminumalloy, is composed of a body and a lid, and has a cooling channel thatis covered with the lid, and in which the lid is metallically joined tothe body, the manufacturing method of a backing plate beingcharacterized in that the lid and body are joined by friction stirwelding.

When the rotation tool that is composed of the shoulder and pin that areused for friction stir welding rotates counterclockwise, it ispreferable that the channel is in the left-hand side to the travelingdirection of the rotation tool. Moreover, when the rotation tool rotatesclockwise, it is preferable that the channel is in the right-hand side.When the rotation tool rotates counterclockwise, a minute defect mayarise in the right-hand side to the traveling direction of the rotationtool rarely. When the channel is located in the right-hand side at thistime, a defect will arise near a wall surface of the channel. However,when the channel is located in the left-hand side, a defect will ariseinside the body and will not arise near the channel. Of course, what isnecessary is just to consider this conversely, when the rotation toolrotates clockwise.

Moreover, the center of the rotation tool which is composed of theshoulder and pin which are used for friction stir welding may be in aposition apart from the channel by more than the maximum radius of a pinsection. Thus, in the friction stir welding, a workpiece receives adownward load of about 10 kN from the rotation tool. If the rotationtool is on the lid above the channel, copper etc. will be deformed andcollapsed due to this load, and a part of a wall will escape into thechannel so that the joining will not be successful. In addition, ingeneral, the geometry of a channel is about 50 W×5 D mm, and thethickness of a lid is about 5 mm.

The lid covering the channel for cooling is larger than the channel, andis made in socket-and-spigot structure with the body. The lid isproduced by machining, where curves with about R 3 to R 10 (unit: mm)are provided in corner sections in order to make it easy to insert thelid into the body. When the lid is joined to the body by the frictionstir welding, it is necessary to perform such curved joining. Asdescribed above, when the rotation tool rotates counterclockwise, adefect may arise in the right-hand side to the traveling direction ofthe rotation tool rarely. Namely, when passing the curves, it isnecessary to relatively lessen a right-hand joining region in order toeliminate a defect in the right-hand side of the rotation tool. Hence,when the rotation tool passes a planar curve (R section), its curvingdirection may be opposite to the rotary direction of the rotation tool.

Generally, in the friction stir welding, joining is performed withslightly leaning a rotation tool backward to the traveling direction.Since the joining of a backing plate is the joining of two-dimensionalplanar surfaces, it is necessary to control a sweepback angle of therotation tool so that the sweepback angle may always become constant toa joining direction. For this reason, it is necessary to have onecontrol axis for it in a joining apparatus. However, according to thepresent invention, a rotation tool does not necessarily need to have asweepback angle. Namely, even if the rotation tool is alwaysperpendicular to a joining material, good-quality joining is possible,and hence, the simplification of the apparatus can be attained. Inaddition, even if a sweepback angle is given to the rotation tool, it isalso possible to join a joining, which becomes a straight line and acurve, only in a straight line. That is, it is also possible to use amethod of joining a planar curve (R section), which becomes a foldingfrom a straight section, in a form composed of two straight lines.

Moreover, in the friction stir welding, since the rotation tool that isrotating forcibly moves against a workpiece, so to speak, the workpiecereceives a large force from the rotation tool. For this reason, it isnecessary to fix a work firmly. In the case of a backing plate,depending on its geometry, it is comparatively easy to fix the body.However, it is comparatively difficult to fix the lid because thechannel winds and has the complicated geometry. Then, it is necessary totemporarily tack-weld the lid to the body beforehand. Unlike permanentjoining, temporary attachment has narrow joining sections and heat inputis not large, and hence, a conventional welding method is alsosufficient. However, it is preferable to perform the friction stirwelding. This is because cost increase due to a plurality of processes.Thus, first, the rotation tool composed of only a shoulder is insertedinto a joining with being rotated. It is necessary to make the amount ofinsertion at this time smaller than the amount of shoulder insertion atthe time of performing permanent joining after this.

Then, the rotation tool is drawn out and this is given to severalpoints. Thereby, as for the joining, only surface sections are joined.After the temporary attachment, the rotation tool is exchanged andpermanent joining is performed.

The present invention is a manufacturing method of a cooling plate whichhas a groove, which becomes a passage of a coolant, inside a body, andin which a lid is joined to the groove, the manufacturing method of acooling plate characterized in that a joining of the body and the lidhas a projection thicker than other sections, and joining to theprojection is performed by friction stir welding owing to insertion andmovement of a rotation tool having a shoulder and a pin, that, while thelid and the body are joined by the friction stir welding, and an airvent is provided in a portion forming the passage, that, while the lidand body are joined by the friction stir welding owing to the insertionand movement of the rotation tool having a shoulder and a pin, and atleast an end section of the joining is formed except the joining, andthat, after the lid and body are partially and temporarily joined by thefriction stir welding owing to insertion of the rotation tool which hasonly a shoulder, and a whole joining is joined by the friction stirwelding.

A projection formed more thickly than other sections in the joining ofthe body and lid is used for preventing cutting in a plane section atthe time of cutting after joining by making the depression depth of thisconcavity into the thickness higher than the plane section since theconcavity is formed in a joining by the insertion of the rotation toolwhich has the shoulder and pin at the time of joining.

An air vent is provided in a section, where a passage is formed, becausenormal joining can be performed by releasing air in the groove to theoutside at the time of installing the lid in the groove at the time ofjoining, and at the time of performing joining by the insertion of therotation tool. Since a groove according to the present invention forms achannel closed inside a body of a cooling plate, it is preferable to usea lid having the same planar surface geometry as the groove. Therefore,they coincide with each other exactly. Hence, the air vent is required.

In an end section of a joining, an insertion hole for a rotation tool isformed. Hence normal joining can be performed by leading the end sectionto the inside of a cooling plate body except the joining, and formingthe insertion hole for the rotation tool in the section.

In conventional electron beam welding or the like, since the deformationof a joining material after joining is large, the front and back facesof a backing plate are ground after correcting a warp after joining.When joining by the friction stir welding is used, since the deformationafter joining can be suppressed, the number of steps can be reduced asdescribed above, and cost reduction is possible. However, since ajoining to be joined by the friction stir welding is joined with arotation tool being inserted in the joining, a burr arises near thejoining, and hence a wall of the joining is made to be thin incomparison with those of other sections. Since the surface smoothness isnot perfect without processing after the joining, surface grinding isneeded in any case. If the joining of the body and lid is partiallythick, it is possible to make the thickness of the joining after thejoining be almost equivalent to that of other sections. Hence, itbecomes possible to decrease surface cutting cost after the joining, andtherefore, it leads to the reduction of manufacturing cost.

The friction stir welding performs solid state welding by pressing arotation tool against a joining, using frictional heat generated in therotation tool and the joining, pushing the rotation tool into thejoining, and stirring materials through moving the rotation tool andgenerating a plastic flow. What becomes a problem here is that aresistance force generated when inserting or moving the rotation tool tothe joining is about 10 kN or mote. For this reason, the structure ofthe joining material that bears this force, and the restraint of thejoining material itself are needed. In the case of a backing plate,depending on its geometry, it is comparatively easy to fix the body.However, it is comparatively difficult to fix the lid because thechannel winds and has the complicated geometry.

Then, it is necessary to temporarily attach the lid to the bodybeforehand. Unlike permanent joining, temporary attachment has narrowjoining sections and heat input is not large, and hence, a conventionalwelding method is also sufficient. However, it is preferable to performthe friction stir welding. This is because cost increase due to aplurality of processes. That is, first, the rotation tool composed ofonly a shoulder is inserted into a joining with being rotated bypreviously performing the friction stir welding on the body and the lid.It is necessary to make the amount of insertion at this time smallerthan the amount of shoulder insertion at the time of performingpermanent joining after this.

Then, the rotation tool is drawn out and this is given to severalpoints. Thereby, as for the joining, only surface sections are joined.After the temporary attachment, the rotation tool is exchanged andpermanent joining is performed. In addition, by performing joining ofonly a curve by conventional welding in the joining of the body and lidof the backing plate, a section where the friction stir welding isperformed becomes only a straight section owing to this, the axialstructure of a friction stir welding apparatus is simplified, and hence,the reduction of apparatus cost is possible.

Furthermore, as for the friction stir welding, a starting point and anending point of joining are different from those in other stationarystates in regard to a heat input and geometry. Since the rotation toolis forcibly inserted in the joining at the starting point, a resistanceforce that the rotation tool receives is large, and the heat input alsobecomes large. It is one of measures to pierce a hole a little smallerthan the pin in an insertion section of the rotation tool in order toreduce the resistance force at the starting point. In addition, the holewith the volume equivalent to the pin is pierced at the ending point, asdescribed above. Hence, these problems are solvable by making thestarting point or the ending point of the joining in the body, which isapart from the cooling hole, or a dummy section prepared separately.

There are various dimensions of backing plates according asapplications. As an example, a backing plate for a sputtering system forlarge-sized flat panel liquid crystal displays has an area of 1 m² ormore. In this case, it is preferable to provide four to five coolingholes each approximately having 50 W×5 H mm in a zigzag direction. Thus,in a large-sized backing plate, since the length of a joining is long,it is desirable to perform joining with a plurality of rotation toolssimultaneous or with providing a fixed distance between a plurality ofrotation tools in a proceeding direction of the joining, rather than oneposition joining at a time with one rotation tool. In addition, sincethe axial structure for controlling each rotation tool is simplified byperforming joining through the plurality of rotation tools moving in thedirections that cross mutually, cost reduction of the joining apparatuscan be attained. Either face of a target can be placed to a coolingplate since it is possible to correct press forming of deformation aftermanufacturing, and subsequently, to finish the target smoothly bygrinding and polishing, but the target may be placed in the sideopposite to a joining face.

Up to now, products manufactured with using the friction stir weldingare, for example, railroad vehicles, vessels, rocket fuel tanks, etc.All of these products are made of aluminum. Although backing plates aremade of aluminum or copper, copper alloys become the main stream becauseof excellent heat conductivity in view of thermal efficiency. Hence, inthe case of copper, both a melting point and a strength are higher ascompared with aluminum, when the friction stir welding is performed, itis necessary to increase temperature of a stirring section to about 700°C. Incidentally, in the case of aluminum, since a fusing point is lowand strength is also low, the temperature is sufficient at only about450° C.

At the time of manufacturing a copper backing plate by the friction stirwelding, several troubles arise since joining temperature becomes highas described above. These are troubles caused by the material beingcopper. First, what is an issue is that a motor and a spindle thatrotate a rotation tool also become hot due to heat transfer since thetemperature of the rotation tool itself also becomes hot because of highjoining temperature. Although there is also exhaustion of the rotationtool itself, exhaustion of an apparatus is rather an issue. In order toperform joining completely, it is not possible to decrease thetemperature of the joining. Therefore, it is necessary to performjoining with spraying a coolant to the rotation tool, which is rotating,in order not to make the frictional heat of the rotation tool andjoining transferred to the apparatus owing to this, the heat transfer tothe spindle is remarkably suppressed, and hence, the long life of theapparatus can be achieved.

In addition, in the case of a large backing plate, joining lengthbecomes long and a heating value also becomes large. At this time, heatis also transferred to a table supporting the backing plate, and hence,the exhaustion of a lubricant of a section driving a table, and inparticular, a circumference moving section becomes an issue. Then, inorder to suppress the heat transfer to the apparatus side such as atable, it is desirable to perform joining with placing the backing plateon a heat sink different from this. Furthermore, in consideration of theabove-mentioned rotation tool life, it is desirable to join the lid,covering one channel, and the body with one rotation tool withoutperforming joining in a long distance with one rotation tool and toperform the next joining after exchanging the rotation tool. Owing tothis, the rotation tool first used is sufficiently cooled whileperforming joining with another rotation tool, and hence, the extensionof the rotation tool life is achieved.

In addition, in the friction stir welding, a burr arises near a joiningas described above. After all of joining is completed, it is possible toexchange the rotation tool for joining to the rotation tool for cuttingand to remove the burr generated in the joining. It is better to performthe exchange of these rotation tools automatically by providing arotation tool magazine and constructing a sequence, rather than manualexchange since the rotation tool has high temperature.

Thus, it becomes possible to manufacture a backing plate, which hassmall heat distortion after joining and has good quality, by producingthe backing plate for sputtering as a cooling plate with using frictionstir welding.

The present invention is a manufacturing method of a cooling plate wherea target material for sputtering is joined on a backing plate serving asa cooling plate, the manufacturing method of a cooling platecharacterized in that the cooling plate is manufactured with themanufacturing method of a cooling plate that is described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan of a backing plate according to the present invention;

FIG. 2 is a cross section of the backing plate according to the presentinvention shown in FIG. 1;

FIG. 3 is a plan showing movement of the rotation tool according to thepresent invention shown in FIG. 1;

FIG. 4 is a microphotography of a cross section after the friction stirwelding according to the present invention;

FIG. 5 is a plan showing the movement of a rotation tool according tothe present invention;

FIG. 6 is a microphotography of a cross section after friction stirwelding according to the present invention;

FIG. 7 is a microphotography of a cross section after friction stirwelding according to the present invention;

FIG. 8 is a sectional view in the case that joining is performed withproviding a projection in a joining of a body and a lid according to thepresent invention.;

FIG. 9 is a plan of a backing plate according to the present invention;

FIG. 10 is a sectional view of the backing plate according to thepresent invention shown in FIG. 9;

FIG. 11 is a plan of a backing plate according to the present invention;

FIG. 12 is a plan of a backing plate according to the present invention;

FIG. 13 is a sectional view of the backing plate according to thepresent invention shown in FIG. 12;

FIG. 14 is a sectional view of a backing plate according to the presentinvention; and

FIG. 15 is a plan of a backing plate according to the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION Embodiment 1

FIG. 1 is a schematic front view of a backing plate as a cooling platemade of oxygen free copper or a copper alloy containing 5% or less of Zror Cr. The backing plate consists of a body 1 and a lid 2. A U-channel 4is provided in the body 1, the lid 2 covers the channel 4, and, the lid2 and channel 4 have the same plane and zigzag geometry although the lid2 and channel 4 differ from each other in dimensions of U-shapes.Otherwise, I-shaped and S-shaped channels or the like are preferable. Inaddition, an R section 3 is provided in each corner section of the lid 2in order to make the lid 2 easily inserted in the body 1. The lid 2 hasthe structure of being received with a step of the body 1, and canreceive the force of the rotation tool 6 on the occasion of the frictionstir weldinq.

The dimensions of the body 1 are 1500 L×1200 W×15 D mm. In he case ofthis FIG. 1, there are five channels 4 for cooling. If he dimensions are1300 L×900 W×15 D mm, similarly, four U-channels 4 are provided. In thisembodiment, there are three channels 4 per one meter long. Each channel4 has an independent closed path, and an entrance and an exit for acoolant are provided in both ends of each channel 4 respectively, andare used after joining. I-shape and S-shape channels are the same as theU-shape channel. An air vent is provided in an end section of the lid 2(not shown). The installation and joining of the lid 2 become easy byproviding the air vent.

In particular, in this embodiment, since joining is performed withfitting the lid 2, which covers the groove, into the groove to the body1 where the groove with a path as a closed channel 4 is formed, there isno mutual expansion of matching sections. Hence, not only good joiningcan be obtained, but also there is no excessive joining because the body1 itself is in one piece, and hence it is possible to obtain a coolingplate with a compact thin shape is obtained also in a large arearegardless of an area.

FIG. 2 is a sectional view near a channel of a backing plate. A firstgroove that becomes the channel 4 whose cross section is rectangular isprovided inside the body 1 by machining, a second groove that has across-sectional space larger than the channel 4 and has a step is formedon the first groove, and the lid 2 is fit in a part of the secondgroove. At this time, the body 1 and lid 2 have socket and spigotstructure, and overlapping width 5 is about 2.5 mm. In addition, thewidth and height of the channel 4 are about 50 mm and 5 mm respectively,and further, the height of the lid 2 is 5 mm. Hence, when the lid 2 isfit into the body 1, both become the same height. Since these shapes ordimensions change according to types of backing plates, a planar shapeof the body 1 also has a round shape besides a square shape in this way.Therefore, a penetration bead of a joining does not go into the channel4, and hence, normal joining is obtained. Since a warp arose in thejoining side of this backing plate after joining, the warp was correctedby press formation with a punch having an I-shaped edge, and thereafter,cutting and grinding were performed.

Next, an embodiment of the friction stir welding will be described. Inthe friction stir welding, the rotation tool 6 composed of a shouldersection 7 and a pin section 8 is inserted in joining material with beingrotated. Then, the rotation tool 6 is moved along a joining line toperform joining. In this embodiment, the diameter of the shouldersection 7 was 15 mm, the maximum diameter of the pin section 8 was 8 mm,and the rotary direction of the rotation tool 6 was made to becounterclockwise. In addition, in the case that the rotation tool 6inclines at three degrees in the direction opposite to the travelingdirection, and the case that the rotation tool 6 does not inclines, anexperiment of the former and the latter was performed under theconditions of a rotation speed of 1300 rpm or 1500 rpm, a joining speedof 270 mm/min or 300 mm/min, and a shift of a centerline of the rotationtool 6 by 3.0 mm or 1.5 mm from a joining beveling in a directionopposite to the channel 4 (offset 3.0 mm or 1.5 mm).

That is, as shown in FIG. 3, joining was performed by traveling therotation tool 6 along the joining line so that the channel might alwaysbe located in the left-hand side. In addition, since a hole 10 is madeat a joining end in the case of the friction stir welding, dummies 9were provided to let them be end sections. All the dummies 9 were cutafter joining of the lid and body. What is important here is therelation among the rotary direction of the rotation tool 6, the channel,and the traveling direction of the rotation tool 6, and hence, it isalso satisfactory to reverse all the left for all the right, and viceversa.

FIG. 4 shows a microphotography of a cross section of a weld bead.Although a weld bead does not have a defect, a joining becomes a littlelow in comparison with other parts since the rotation tool 6 is inserteda little in a joined material. However, as described above, a surface ofa backing plate needs to be smooth, and hence, anyway, such a concavityis satisfactory because of performing the machining of the surface. Inaddition, although a part that is equivalent to a concavity of the weldbead that is released to the outside becomes a burr, this issatisfactory because of the same reason. However, the amount ofmachining at that time was an amount to be machined in the time that was¼ or less in comparison with a conventional welding method. This isbecause a cutting step for correcting a bent after joining and smoothinga surface was shortened sharply since the heat distortion of the joiningby the friction stir welding method is small, that is, 1/10 of that inthe case of electron beam welding. In addition, it is clear that normaljoining is obtained without spilling out the weld bead at the time ofjoining into the channel 4 since the weld bead are formed in the outsideof the lower left channel 4 as shown in FIG. 4. The joining is performedso that a concavity may be made by pressing the shoulder 7. Moreover,each of the start and stop of the rotation tool was performed in aposition apart from the joining. TABLE 1 Number of tests Fractiondefective Junction method (value) (%) Friction stir welding 126 0Electron beam welding 60 5

Table 1 shows the result of helium leakage test of the channel 4 by thismethod. The leakage test is performed at 1×10⁻⁷ Pa, and a material for acurrent method, that is, an electron beam welding material was used as acomparison material. Although, in the case of the friction stir weldingmaterial, the fraction defectives were 0% in the case that the rotationtool 6 inclines at 2 degrees and the case that it does not incline andall are accepted, but the fraction defective was high, that is, 5% inthe case of the electron beam welding material. In this case, withconsidering repair cost because a leaking section must be repairedagain, a cost merit of the friction stir welding is very large.

A target for sputtering can be made by any one of brazing, friction stirwelding, and electron beam joining, and can be placed in the joiningside of the lid 2 or its opposite side, but it is preferable to placethe target in the joining side.

Embodiment 2

This embodiment relates to the joining of the backing plate similar tothat in FIG. 1, and in particular, a joining example about the R section3 will be described. The rotation speed of a rotation tool, joiningspeed, and rotation tool geometry are the same as those in the firstembodiment. As shown in FIG. 5, after first inserting the rotation tool6 in a position “a”, joining was performed in the path of a→b→c→d underthe above-described conditions, and the end section 10 was made to bethe dummy 9. Next, after inserting the rotation tool 6 in a position “a”again, joining was performed in the path of a→e→f→d, and the end section10 was similarly treated. What is important at this time is that therotation tool 6 always turns to the right in the R section 3. When therotary direction of the rotation tool is clockwise contrary to this,what is necessary is just to perform joining so that the rotation toolmay always turn to the left. Although a defect did not arise in ajoining in any cases, a minute defect as shown in FIG. 6 may arise inthe R section if the rotary direction and the turning direction of therotation tool become contrary to the above in rare cases. However, sincea defect having this level of size does not harmfully affect onleak-proof property, this is satisfactory. In addition, in thisembodiment, the other structure and joining methods are the same asthose of the above-described ones.

As for the joining, in this embodiment, although the R section 3 ispresent, it is possible to form the section by straight lines. Moreover,a weld bead was formed in the outside of the lower left channel 4 asshown in FIG. 6 without the weld bead spilling out to the channel 4, andfurthermore, its penetration bead exists in the body. Hence, it isapparent that normal joining can be obtained.

Embodiment 3

What are examined in this embodiment are the overlapping width 5 shownin FIG. 2, and the distance (offset) apart from a joining beveling ofthe centerline of the rotation tool 6 in a direction opposite to thechannel 4. The geometry of the rotation tool that is used is the same asthat in the first and second embodiments. In addition, joiningconditions are the same. TABLE 2 Overlapping Maximum radius width Offsetof pin State of w (mm) x (mm) W + x (mm) r (mm) joining 2.5 0 2.5 4.0Collapse 2.5 1 3.5 4.0 Collapse 2.5 1.5 4.0 4.0 Good 1 0 1.0 4.0Collapse 2 0 2.0 4.0 Collapse 3 0 3.0 4.0 Collapse 4 0 4.0 4.0 Good

As shown in Table 2, in order to obtain normal joining, it is preferablethat w+x≧r. That is, it is required for that the weld bead that isformed is in the outside of the channel. Moreover, a reason why thesample was not successful in joining is that the lid was collapsed dueto the load received from the rotation tool.

Embodiment 4

In this embodiment, the temporary attachment of the lid was examined. Amicrophotography of the cross section of the temporary attachmentsection is shown in FIG. 7. The temporary attachment was performed withusing a rotation tool, which did not have a pin section and had ashoulder with 13 mm of diameter, at a rotation speed of the rotationtool of 1500 rpm at a rate of 12 temporary attachments per lid. As shownin FIG. 7, the temporary attachment section is joined at a depth ofabout 2 mm. Next, permanent joining was performed under the sameconditions as those in the first embodiment. In consequence, the lid wasfirmly fixed by the temporary attachment and the permanent joining wasperformed with sufficient accuracy. Thus, it turns out that, in thefriction stir welding, firm fixation of a joining material is importantand temporary attachment can be surely and easily performed withoutusing another method.

Embodiment 5

This embodiment is the case that a projection with locally thickstructure is present near a joining of a body and a lid. FIG. 8 shows anexpanded sectional view of the vicinity of the joining according to theembodiment. It is the characteristic that the above-described thicknessof the body and lid 2 is locally thick, and other dimensions etc. arenot changed from those in the first embodiment. Here, it is desirablethat the width of the thick convexities 11 and 12 is almost equivalentto or a little larger than the diameter of the shoulder 7 of theabove-described rotation tool 6. In addition, it is desirable that thethick convexities 11 and 12 are higher than other parts by 0.3 to 2 mm.After joining, the joining height does not become low like that in thefirst embodiment, and hence, it is possible to simplify a subsequentsurface cutting step. In addition, in this embodiment, the otherstructure and joining methods were the same as those in the above.

Embodiment 6

FIG. 9 is a plan of a backing plate where a channel has I-shapedstructure. In addition, FIG. 10 is a sectional view of the vicinity ofthe channel. The body 1 and a lid 2 are made of oxygen free copper. Thedimensions of the body 1 were 1200 L×900 W×15 D mm, and dimensions offive channels 4 are 40 W×5 H mm respectively. Moreover, in the R section3, R=3 mm and overlapping width 5 is 5 mm. In addition, joiningconditions, i.e., rotation tool geometry, rotation speed, and joiningspeed are the same as those in the first embodiment, and an offset ismade to be zero. In addition, the rotation tool 6 is inclined at 2degrees in the direction opposite to the traveling direction. Inaddition, in this embodiment, the other structure and joining methodsare the same as those of the above-described ones.

In this embodiment, in order to make the above-described channel 4airtight, the joining of the lid 2 was joined with using two rotationtools 6. First, the lid 2 is temporarily attached to the body 1 with therotation tools constituted only by a shoulder respectively. Next, thelid 2 and body 1 were joined along joining lines a-a′ and b-b′ withusing the two rotation tools 6. Since the distance of joining lines a-a′and b-b′ is narrow, that is, about 50 mm, the two rotation tools 6 keepa gap (L) so that they may not interfere mutually. At this time, L isabout 200 mm. Next, joining was performed along the joining lines c-c′,d-d′, e-e′, and f-f′ one by one. Next, joining was performed along thejoining lines a-j and a′-j′ simultaneously. At this time, R=3 mm in theR section 3, and the diameter of the pin was 8 mm, and the R section 3was joined along two joining lines that were orthogonal to each other.Hence, it becomes possible to perform the above-described joining onlyin linear joining, and therefore, it becomes possible to simplify thestructure of the above-described joining apparatus and to reduce thecost of the apparatus. In addition, also in this embodiment, dummies 9were used for all of starting points and ending points of joining, andthe dummies 9 were cut after the completion of joining.

By the way, in this embodiment, since two rotation tools were used forsimultaneously performing joining, the frictional heat generated in therotation tools and joining was large. For this reason, joining was triedwith flowing cooling water in the vicinity of a joining, the wholebacking plate and the channel. Although joining conditions were almostequivalent to the case where no cooling water was supplied, the rotationspeed of rotation tools was set to 2000 rpm owing to this, the surfacetemperature of a part of the body 1 which was separated from a joiningby about 4 mm was 100° C. or less, which was a half of heat distortionafter joining in the case of no water-cooling. Hence, correction ofdistortion after joining becomes unnecessary. In addition, since thetemperature of a joining was about 700° C., water was boiled at thepart, but there was no penetration of moisture into the joining, andhence, there was neither generation of a defect nor deterioration ofmechanical characteristics.

Embodiment 7

FIG. 11 is a plan of a backing plate that has reverse S-shaped channels4. The body 1 and a lid 2 are made of oxygen free copper. Although theplanar shapes of the channel 4 and lid 2 are the same, dimensions differa little. The lid 2 is integrated. The dimensions of the body 1 are 1200L×900 W×15 D mm, and dimensions of two or four channels 4 are 40 W×5 Hmm respectively. Moreover, in the R section 3, R=15 mm and overlappingwidth 5 is 5 mm. In addition, joining conditions, i.e., rotation toolgeometry, rotation speed, and joining speed were the same as those inthe first embodiment, and an offset was made to be zero. In addition,the rotation tool 6 was inclined at 2 degrees in the direction oppositeto the traveling direction. In this embodiment, TIG welding was used fortemporarily joining the R section. First, the lid 2 was fit in the body1, and a section (TIG section) shown by thick lines in FIG. 11 wasjoined by the TIG welding. Next, the friction stir welding of a joiningto be joined was performed with using the rotation tool 6. At this time,since a locus of the rotation tool became only in the verticaldirection, for example, on this paper, a joining apparatus became anapparatus that was simplified by having control only in the verticaldirection on this paper. Hence, it is possible to achieve cost reductionof a facility.

Embodiment 8

FIG. 12 is a schematic diagram of a backing plate. The body 1 and a lid2 are made of oxygen free copper. In addition, FIG. 13 is a sectionalview of the vicinity of the joining of FIG. 12. Geometry, joiningconditions, etc. of the body 1 are the same as those in the seventhembodiment. Moreover, the lid 2 has an air vent in an end section, andis integrated in a U-shape. In this embodiment, life extension of therotation tool 6 was examined. The body 1 was fixed on the heat sink 14that had a channel through which a coolant circulated inside. Inaddition, there was a cooling system 15, which cooled the rotation tool6, near the rotation tool 6, and which sprayed a cooling gas 16 on therotation tool 6. It turns out that the surface temperature of therotation tool 6 increases to about 400° C. during joining. If the motoror spindle rotating the rotation tool 6 is exposed to such hightemperature, it will malfunction. When a motor with 5 kW of output wasused, the temperature of the spindle rose due to heat transfer from therotation tool 6, and when there was no cooling system 15, a safetydevice was often activated to stop the motor.

An inert gas besides air is also sufficient as the cooling gas 16, and aflow rate was 10 L/min. Since the surface temperature of the rotationtool 6 became about 150° C. by using the cooling system 15, it becamepossible to prevent the damage of the rotation tool 6. In addition, ifmoisture etc. remains in the channel 4 after manufacturing in regard toa backing plate, there is a possibility of surface contamination arisingbecause the moisture adheres to a surface used as a product at the timeof subsequent conveyance etc. Hence, there is a case that underwaterfriction stir welding is not suitable. In this case, another heat sink14 different from this was used as a method for distortion reduction.Since the 20° C. coolant always circulated in the heat sink 14, it waspossible to lessen heat distortion by the friction stir weldingsimilarly to that by the underwater friction stir welding. In addition,all joining was performed by NC control in this embodiment. Junction wasperformed with using one rotation tool per channel.

The procedure of joining of a left lid in FIG. 12 is as follows. Therotation tool was first moved in order of d→f→e→a→b→c→d under theabove-described joining conditions after inserting the rotation tool 6in a dummy 9, and the end section 10 was set on the dummy 9. The tracingof these rotation tools 6 was performed by using an NC controller notshown. Next, the rotation tool was exchanged to a rotation tool 6reserved in a tool magazine 17. Then, the following lid was joined.Since a rotation tool is cooled within the rotation tool magazine 17 byexchanging a rotation tool every lid and performing joining, the load ofthe rotation tool is reduced. In a phase of the completion of joining ofall lids, next, the rotation tool was exchanged to a tool 18 for cuttingin the tool magazine 17, and the processed face of the backing plate wassmoothed. Such a series of processes was fully automated by programminga sequence.

A conventional manufacturing method has complicated steps as follows:

(1) Washing of a backing plate (because it is necessary to removecontamination in order to perform joining in vacuum in subsequentelectron beam welding),

(2) Fixation of a backing plate to a jig for electron beam welding,

(3) Vacuum pumping,

(4) Electron beam welding,

(5) Vacuum leakage test and removal from the jig,

(6) Heat treatment for removal of heat distortion, and

(7) Smoothing by cutting.

According to a method like the present invention, it is possible toperform a series of processes like these only by one apparatus byexchanging a tool, and it is also unnecessary to perform heat treatmentfor removal of heat distortion. Hence, it is possible to understand thatwelding is a machining process that is a direct extension of machining,productivity is high, and sharp reduction of manufacturing cost can beachieved.

Embodiment 9

FIG. 14 is a sectional view of a lid and a backing plate, the lid whosegeometry is the same as that of a backing plate. The body 1 and a lid 2are made of oxygen free copper. The thickness of the body 1 is 10 mm,and the channel 4 is at a width of 30 mm, a height of 5 mm, and a spaceof 15 mm. In addition, the lid 2 covers all the channels that are morethan one, and joining is performed by lap joint of the lid 2 and thebody 1. The geometry of the channel is the same as that in theabove-described embodiments, and the channel having a closed path isused. Therefore, one air vent is provided in an edge of each channel. Asfor the geometry of the rotation tool, a diameter of the shouldersection 7 is 14 mm, and the maximum diameter of the pin section 8 is 8mm and length is 7 mm. Rotation speed and joining speed were the same asthose in the first embodiment, and a middle section of adjacent channelswas joined. In addition, the rotation tool 6 was inclined at 2 degreesin the direction opposite to the traveling direction.

In this embodiment, although a joining form was not butt joint but waslap joint, no defect was generated in joining parts, and heatdeformation at the time of joining was also small, and hence this wasmanufacturable. Thus, a backing plate can be manufactured according tothis process regardless of joint geometry. In this embodiment, theperimeter of the backing plate and all the spaces between channels werejoined according to the planar surface geometry of the channels.Junction using a dummy can be performed similarly. The press forming,grinding, and polishing after joining as well as the above described canbe performed.

Embodiment 10

FIG. 15 is a plan at the time of the channel 4 being formed in an oblongM-shape in the long backing plate. The body 1 and a lid 2 are made ofoxygen free copper. The dimensions of the body 1 are 2000 L×300 W×15 Dmm, and the channel 4 is at a width of 30 mm, a height of 5 mm, and aspace of 15 mm. In addition, the lid 2 has the same planar surfacegeometry as the channel, length and width of the lid 2 are formed alittle largely than those of the channel 4, and a cross section thereofis the same as that of the first embodiment. The joining of the lid 2and the body 1 is butt joint. The geometry of the channel is the same asthat in the above-described embodiments, and the channel having a closedpath is used. Moreover, one air vent is provided in an edge of achannel. As for the geometry of the rotation tool, a diameter of theshoulder section 7 is 14 mm, and the maximum diameter of the pin section8 is 8 mm and length is 7 mm. Rotation speed and joining speed were thesame as those in the first embodiment, and a middle section of adjacentchannels was joined. In addition, the rotation tool 6 was inclined at 2degrees in the direction opposite to the traveling direction.

In this embodiment, a joining form was the same as the butt joint in theabove described, no defect was generated in joining parts, and heatdeformation at the time of joining was also small, and hence this wasmanufacturable. An end section of a weld bead was provided except thejoining. In addition, joining using a dummy can be performed similarlyas described above. The press forming, grinding, and polishing afterjoining as well as the above described can be performed.

According to the present invention, it is possible to obtain a coolingplate that has normal joining by friction stir welding. In consequence,it is possible to obtain a backing plate having high coolingeffectiveness, small heat distortion, a thin shape, large-area geometry,and good quality.

1. A cooling plate comprising: a body having a groove which becomes acoolant passage; and a lid having a width larger than a width of thegroove so that the body and the lid have a socket-and-spigot structure;wherein the body and the lid are joined to each other by friction stirwelding; wherein a weld bead formed by the friction stir welding isoutside the groove; and wherein a center of the weld bead is positionedat a distance from the groove at least equal to a width of thesocket-and-spigot structure which is half of a width difference betweenthe lid and the groove.